In a prior-art joint used in a piping system of a feed-water system or a hot-water supply system, a pipe insertion space is formed between an inner tubular portion and an outer tubular portion extending in an axial direction of the joint main body, and a cap (lid) is fitted on the outside of the outer tubular portion. A retainer mechanism for retaining a pipe inserted into the insertion space is provided between the outer tubular portion and the cap. The pipe is retained by the retainer mechanism when a withdrawing force acts on the pipe.
A joint of this type has been proposed by the present applicant in Patent Document 1. The joint includes a joint main body having an insertion space (insertion chamber), into which the pipe is inserted and a cap (lid) to cover the insertion space. The joint main body and the cap are connected to each other at a joint portion, and a holding body is fitted into the outer periphery of the cap. The joint main body and the cap are locked by a serrated locking portion. A retainer ring for retaining the pipe inserted into the insertion space is provided between the outer tubular portion and the cap. According to this joint, since the holding body holds the cap and the joint portion to cover them, even when a withdrawing force acts on the pipe, the cap and the joint portion is maintained in the original state.